Fuel rail assemblies for supplying fuel to fuel injectors of internal combustion engines are well known. A fuel rail assembly, also referred to herein simply as a fuel rail, is essentially an elongated tubular fuel manifold connected at an inlet end to a fuel supply system and having a plurality of ports for mating in any of various arrangements with a plurality of fuel injectors to be supplied. Typically, a fuel rail assembly includes a plurality of fuel injector sockets in communication with a manifold supply tube, the injectors being inserted into the sockets.
Fuel injectors may be divided generally into multi-port fuel injectors (MPFI), wherein fuel is injected into a runner of an air intake manifold ahead of a cylinder intake valve, and direct injectors (DI), wherein fuel is injected directly into the combustion chamber of an engine cylinder, typically near the end of the compression stroke of the piston. Since a direct injector is exposed to the pressures within a cylinder, a DI fuel rail assembly must handle significantly higher fuel pressures than a MPFI fuel rail assembly in order to provide precisely metered fuel into a cylinder's combustion chamber.
Because of the higher operating pressures, typically, DI fuel systems employ fuel injectors that are rigidly supported on the engine's cylinder head. The rigid connection between the cylinder head and injector provides enough structural support to withstand the higher operational pressures. However, such a rigid connection has a drawback in that the metal-to-metal contact of the rigid connection provides a direct path for transmitting injector noise. Current MPFI technology includes a hanging injector system that avoids the rigid connection between the cylinder head and the injector by suspending the injectors from the fuel rail via a mechanical coupling. However, while such a coupling solves the noise transmission problem of a rigid connection, the hanging injector connection employed by MPFIs cannot withstand the operating pressures of a DI system.
What is needed in the art is a fuel injector to fuel rail connection that is able to mechanically support loads originating from relatively high fuel pressures and from combustion pressure of direct injection fuel injection systems.
It is a principal object of the present invention to provide a high-pressure fuel injector coupling that easily connects a DI fuel injector to a fuel rail and that is able to manage relatively high separating loads between the fuel rail and the fuel injector due to relatively high DI fuel pressure levels.